A mechanism for driving a means of transport comprising a frame

Abstract: The invention relates to a mechanism for driving a means of transport comprising a frame by human force and/or with a mechanical driving source. A part to be rotated by human force (2) is coupled, by resiliently deformable means, to a driven part, which is to be rotated so as to drive the means of transport. Monitoring means are provided for determining the angular displacement between the two parts, with a view to influencing said mechanical driving source through control means. A permanent magnet (23,24) is connected to the part to be rotated by human force (2) as well as to the driven part which is rotated, and sensors are provided on the frame in such a manner, that with each revolution of the rotatable parts the sensors detect the passage of a respective magnet (23,24), so as to generate signals influencing the control means.

Description: The invention relates to a mechanism for driving a means of transport comprising a frame by human force and/or with a mechanical driving source, whereby a part to be rotated by human force is coupled, by resiliently deformable means, to a driven part, which is to be rotated so as to drive the means of transport, whilst monitoring means are provided for determining the angular displacement between the two parts and the speed of said rotating parts, with a view to influencing said mechanical driving source through control means. Such a mechanims is described in US Patent No. 5,024,286, more in particular used in a bicycle equipped with an auxiliary motor. Although the present application also describes an embodiment wherein the mechanism is used in a motor-assisted bicycle, it will be apparent that the mechanism according the invention can also be used in other vehicles and/or craft, for example in a motor-assisted pedal boat. The bicycle known from US Patent No. 5,024,286 has two discs extending parallel to each other and being provided with openings at their circumference, said discs being used for determining the angle of displacement between the part rotated by human force and the part being driven. In the unloaded position of the parts the openings in the one discs are covered by parts of the other disc. During operation the discs will generally rotate more or less with respect to each other, as a result of which the apertured parts of the discs will overlap each other to a larger or smaller extent. An optical sensor is used for detecting the extent to which the apertured parts of the discs overlap as well as the passage of said overlapping openings, in order to generate signals for influencing the control means of the mechanical driving source, all this as explained in the above-mentioned US Patent No. 5,024,286, the contents of which are incorporated herein by reference. Although the device may be statisfactory per se, the fact that the use of an optical sensor requires power constitutes a drawback, whilst such a mechanism is furthermore highly sensitive to fouling of the optical sensor. Accordingly the object of the invention is to obtain a mechanism of the above kind, which has a simple, efficient construction and which can operate in a reliable manner. According to the invention this can be achieved in that said two parts are provided with a plurality of magnets, which are arranged in regularly spaced-apart relationship, and that sensors are provided on the frame in such a manner, that with each revolution of the rotatable parts the sensors detect the passage of the magnets as well as a change in circumferential direction between the magnets on said two parts, so as to generate signals influencing the control means. Preferably so-called reed sensors will be used, which are opened or closed upon passage of the magnets. According to a further aspect of the invention a particularly efficient connection between the part to be rotated by human force and the driven part can be made when both parts are connected by a connecting member which is provided with two rings concentrically surrounding each other, one of said rings being connected to the one part of the other ring being connected to the other part, whilst the two rings are interconnected by spokes made of a resilient material. In this way a construction of simple design is obtained, by means of which a comparatively great deal of power can be transmitted. It is noted that EP-A-0079573 discloses a mechanism for driving a means of transport whereby the two parts coupled to each other by resiliently deformable means each have been provided with a ring-shaped magnet arranged co-axially around the axis of rotation of said two parts. In said known structure there is detected only the amount of human force exerted during operation by measuring a change of the distance between the two ring-shaped magnets in axial direction. The invention will be explained in more detail hereafter with reference to a possible embodiment of the construction according to the invention diagrammatically illustrated in the accompanying figures. Figure 1 shows a sprocket wheel of a bicycle with parts associated therewith, partly in elevation and partly in section. Figure 2 is a side view of figure 1, partly in elevation and partly in section, along the line II. Figure 3 is a sectional view, along the line III, of a part of Figure 1. As is illustrated in the Figures, a disc-shaped means 2 is fixed to a crankshaft 1 by means of a hub 4 of the disc-shaped means 2, which is clamped down on the crankshaft 1 by means of a bolt 3. A pair of usual cranks 5, only one of which is shown, on whose free ends pedals (not shown) are pivotally mounted in the usual manner, is fixedly connected to said disc-shaped means. It will be apparent, therefore, that the crankshaft 1 with the disc-shaped means 2 can be rotated about the axis of rotation of the crankshaft 1 in the usual manner with respect to the frame of the bicycle or other vehicle, in which the crankshaft will be journalled so as to be rotatable about its axis. An annular means 8 of L-shaped section is fixed to the hub 1 by means of screws 7, whereby, as will be apparent from the Figures, one leg 9 of the annular means 8 abuts against one end of the hub 4 and the other leg 10 of said annular means 8 tightly surrounds part of the outer periphery of the hub 4. Connected to the outer periphery of the leg 10 are the ends of spokes arranged in ten regularly spaced groups, each group comprising two spokes 11 and 12. The outer ends of the spokes 11 and 12 are connected to an annular means 13 concentrically surrounding the annular means 8, and more in particular to cams 15 projecting in the direction of the annular means 8 with respect to the annular flange 14 of the annular means 13. As is furthermore apparent in particular from Figures 2 and 3, a circular rib 16 is provided on the outside of the circular flange 14, on which two sprocket wheels 17 and 18 are clamped down by means of bolts 19. The connecting means connecting the sprocket wheels 17 and 18 to the hub 4 and the disc-shaped means 2, which is comprised of the two annular means 8 and 13 and the spokes 11, 12 connecting said annular means, is preferably integrally formed of plastic material. As is apparent from the Figures thereby, the spokes have a more or less S-shaped or curved extension, whilst the spacing between the ends of the spokes 11 and 12 joining the annular means 8 is smaller than the spacing between the ends of the same spokes 11 and 12 joining the annular means 13. As is furthermore apparent the spokes of the illustrated preferred embodiment have a substantially rectangular section, whereby the longitudinal side of the rectangle extends at least substantially parallel to the central axis of the crankshaft 4. As is furthermore illustrated in the Figures the disc-shaped means is provided with projecting noses 20 being integral with the disc-shaped means, in such a manner that each nose is located between a pair of projecting cams 15 of the annular means 13. In the illustrated rest position of the parts each nose 20 abuts against one side of a cam 15, whilst a compression spring, a coil spring 21 in this embodiment, is provided between the nose 20 and the opposite cam 15. The spring is thereby retained in position by pins 22 surrounded by the coil spring 21, which are secured to the nose 20 and to the cam 15 respectively. Each of the cams 20 houses a permanent magnet 23, whilst each of the cams 15 accommodates a permanent magnet 24. The distance between the central axis of the crankshaft 1 and the permanent magnets 23 is different from the distance between the central axis of the crankshaft and the permanent magnets 24. In the present case the permanent magnets 24 are located further away from the central axis of the crankshaft than the permanent magnets 23. Assuming that the mechanism described above and illustrated in the Figures is incorporated in a bicycle, one of the sprocket wheels 17 or 18 will be connected, by means of a chain, to a sprocket wheel mounted on a bicycle wheel, whilst the other sprocket wheel will be connected by means of a chain to a sprocket wheel mounted on the outgoing shaft of an auxiliary motor or the like. When using a means of transport equipped with the above-described mechanism, the user of said means of transport will be able to rotate the part consisting of the hub 4 and the disc-shaped means 2 via the cranks 5 by human force. Said part rotated by human force will thereby rotationally drive the annular means 13 with the sprocket wheels 17 and 18 mounted thereon via the springs 21 and the spokes 11 and 12, said sprocket wheels constituting a driven part to be rotated for driving the means of transport. Upon rotation of these parts the above-described permanent magnets 23 and 24 will also be rotated, of course. Sensors provided on the frame, preferably so-called reed switches, which will be opened or closed upon passage of a magnet, dependent on their design and/or arrangement, may in the first place be used to establish the passage of the magnets 23, 24 and thus determine the number of revolutions of the parts carrying the magnets in question. In addition to that a certain angular displacement may occur by deformation of the springs 21 and the spokes 11 and 12 (dotted lines), dependent on the forces exerted on the pedals and the power to be transmitted via the driven part 13, 17, 18, whereby, measured in circumferential direction, the distance between the permanent magnets 23 and 24 will change. This relative rotary motion is limited by the pins 22 touching each other at a certain point. Also the distance or the variation in this distance respectively will be detected during the rotation of the means 2 and 13 by the sensors provided on the frame. Thus the sensors may generate signals, which provide an indication of the number of revolutions of the rotating parts and of the angular displacement between the two parts, and thus of the force exerted by the user of the vehicle. This information may be used, for example in the manner described in the aforesaid US Patent 5,024,286, to influence an auxiliary motor or the like driving source for driving the vehicle. It will be apparent that by using permanent magnets and switch(es) to be influenced by means of the magnetic field reliable detecting means of simple design are obtained, which do not require the supply of electric energy or the like for their operation. The connecting means, preferably made of plastic material, provided between the two parts, which is built up of two annular means 8 and 13 concentrically surrounding each other and the spokes 11, 12 provided therebetween, can furthermore be produced and mounted in a simple manner interconnecting the two parts, whilst allowing a relative rotation of the said two parts with respect to each other.

Claims: A mechanism for driving a means of transport comprising a frame by human force and/or with a mechanical driving source, whereby a part (1-4) to be rotated by human force is coupled, by resiliently deformable means (11, 12, 21), to a driven part (16-18), which is to be rotated so as to drive the means of transport, whilst monitoring means are provided for determining the angular displacement between the two parts (1-4; 16-18) and the speed of said rotating parts (1-4; 16-18), with a view to influencing said mechanical driving source through control means, characterized in that said two parts (1-4; 16-18) are provided with a plurality of magnets (23, 24), which are arranged in regularly spaced-apart relationship, and that sensors are provided on the frame in such a manner, that with each revolution of the rotatable parts (1-4; 16-18) the sensors detect the passage of the magnets (23, 24) as well as a change in distance in circumferential direction between the magnets (23, 24) on said two parts (1-4; 16-18), so as to generate signals influencing the control means. A mechanism according to claim 1, characterized in that reed sensors, to be operated by said magnets (23, 24), are provided on the frame. A mechanism according to claim 1 or 2, characterized in that the magnets (24) connected to the one part (16-18) are disposed at a larger distance from the common axis of rotation of the two parts than the magnet (23) connected to the other part (1-4). A mechanism according to any one of the preceding claims, characterized in that the two parts are connected by a connecting means (8-13), which is provided with two rings (10; 14) concentrically surrounding each other, one (10) of said rings being connected to the one part (1-4) and the other ring (14) being connected to the other part (16-18), whilst the two rings are inter-connected by spokes (11, 12) of a resilient material. A mechanism according to claim 4, characterized in that the connecting means (8-13) is integrally formed of plastic material. A mechanism according to claim 4 or 5, characterized in that said spokes (11, 12) have a curved, in particular an S-shaped extension. A mechanism according to any one of the claims 4 - 6, characterized in that said spokes (11, 12) are of rectangular section, whereby the longitudinal side of said rectangular extends at least substantially parallel to the axis of rotation of the two parts (1-4; 16-18). A mechanism according to any one of the claims 4 - 7, characterized in that said connecting means (8-13) is provided with cams (15), between which noses (20) connected to the part (1-4) to be rotated by human force are located, whilst between said noses (20) and said cams (15) springs (21) are provided, which attempt to push the noses (20) and the cams (15) in a direction away from each other. A mechanism according to claim 8, characterized in that said magnets (23, 24) are mounted in said noses (20) and in said cams (15).

Inventors: KUIJPERS JEROEN NICOLAAS M, SHIKIMORI SEIJI, KUIJPERS, JEROEN NICOLAAS MICHAEL, SHIKIMORI, SEIJI
Applicants: YAMAHA MOTOR EUROP, YAMAHA MOTOR EUROPE N.V.
Application year: 1994
Main classification: B62M23
IPC codes: G01L3, B62M9, B62M6